There is increasing evidence that limbic regions of the human brain are particularly susceptible to pathogenic processes in schizophrenia. For example, our group has identified alterations in DA receptor density, DA terminal density, beta receptor density, serotonin terminal density and serotonin receptor density in the limbic zones of the striatum of the hippocampus of schizophrenics. Our strategy has been to identify receptor systems that are expressed differentially in these regions in the human as compared to other regions or to non-human brain. When these are identified, their anatomical distribution is then mapped in schizophrenic as compared to nonschizophrenic brain tissue. In order to evaluate the morphological status of these affected systems in more detail, high resolution techniques are now being employed. The localization of receptors and terminals at the cellular level and the determination of whether disturbances in the expression, insertion and organization of these receptors plays an important role in the clinical symptoms associated with schizophrenia are important goals of this program.